1. Field of the Invention
This invention relates to a plasma display panel, and more particularly to a plasma display panel of the AC (Alternating Current) type and the surface discharge type.
2. Description of the Related Art
Conventionally, various image display apparatus are utilized, and one of such image display apparatus is an apparatus called plasma display panel.
The plasma display panels an image by causing a phosphor to emit light by discharge and is anticipated as a display in the form of a flat plane which spontaneously emits light in a high luminance.
Plasma display panels of the type mentioned are divided into two types of a DC (Direct Current) type and an AC type. Since an AC plasma display panel has electrodes which are not exposed to a discharge space, it is superior in durability to a plasma display panel of the DC type whose electrodes are exposed to a discharge space.
Also AC plasma display panels are divided into two types including an opposing type and a surface discharge type. While electrodes of a plasma display panel of the opposing type which extend in perpendicular directions to each other are opposed to each other, a plasma display panel of the surface discharge type includes surface discharging electrodes which include scanning electrodes and sustain electrodes in combination and are arranged on a plane.
A plasma display panel of the surface discharge type of the AC type is anticipated as a large-size full-color flat display since it has a wide memory margin and a high light emission efficiency.
Such a plasma display panel of the surface discharge type of the AC type as described above is disclosed, for example, in Japanese Patent Laid-open No. 320667/96.
Japanese Patent Laid-open No. 320667/96 discloses that some wiring patterns are omitted by devising a driving method.
Here, the plasma display panel disclosed is described below as a conventional example with reference to FIGS. 1 to 3.
It is to be noted here that, in order to simplify the description, the horizontal direction of FIG. 1 is referred to as the row direction while the vertical direction is referred to as the column direction. The row direction is a direction parallel to the rows, and a plurality of columns are arranged successively in the row direction. The column direction is the direction parallel to the columns, and a plurality of rows are arranged in the column direction.
Plasma display panel 1 of the surface discharge type of the AC type described as an example here includes, as shown in FIG. 1, display panel 2 and drive circuit 3. Display panel 2 and drive circuit 3 are connected to each other.
On display panel 2, n surface discharge electrodes 11 parallel to the row direction are successively arranged in the column direction. Each of the surface discharge electrodes 11 is composed of scanning electrode 12 arranged at a higher location and sustain electrode 13 located at a lower location.
Positioned on the rear side of surface discharge electrodes 11 is discharge space 16 in which gas of a phosphor is enclosed. On the rear side of surface discharge electrodes 11, m data electrodes 14 parallel to the column direction are successively arranged in the row direction.
In particular, as shown in FIG. 2, scanning electrodes 12 and sustain electrodes 13 which compose surface discharge electrodes 11 are formed by printed wiring lines on the rear face of transparent substrate 17. Data electrodes 14 are formed from printed wiring lines on the front face of transparent substrate 18 formed as a separate member.
Phosphor 20 is positioned on the front face of each of data electrodes 14 with dielectric 19 interposed therebetween, and discharge space 16 is formed at a position opposing phosphor 20.
As described above, n surface discharge electrodes 11 and m data electrodes 14 extend perpendicularly to each other with discharge space 16 interposed therebetween. Each of n.times.m intersecting points between n surface discharge electrodes 11 and m data electrodes 14 with discharge space 16 interposed therebetween serves as pixel 15 which emits light individually.
As shown in FIG. 1, one scanning wiring line 21 is connected to the left ends of n scanning electrodes 12. One scanning driver 22 is connected to this one scanning wiring line 21.
One sustain wiring line 23 is connected commonly to the right ends of n sustain electrodes 13. One sustain driver 24 is connected to this one sustain wiring line 23.
m data drivers (not shown) are individually connected to m data electrodes 14. Drive circuit 3 is formed by such various drivers 22 . . . as described above.
It is to be noted that planar grounding electrodes (not shown) are formed on the rear faces of electrodes 12 to 14 arranged in such a manner as described above. A ground potential is applied to the grounding electrodes.
Plasma display panel 1 of the surface discharge type of the AC type having such a structure as described above can display a desired image in a dot matrix system by individually controlling n.times.m pixels arranged in a matrix so that they should or should not emit light.
Here, a driving method for plasma display panel 1 having the construction described above is described with reference to FIG. 3.
First, as a preparation operation, n scanning drivers 22 and one sustain driver 24 apply a predischarge pulse to n scanning electrodes 12 and sustain electrodes 13. Consequently, by the predischarge, display panel 2 is put into a condition wherein discharge of an image display is executed stably.
Then, n scanning drivers 22 apply scanning pulses SC1 to SCn, whose timings are successively shifted relative to each other, individually to n scanning electrodes 12, and in synchronism with the timings, the m data drivers apply data pulses to particular data electrodes 14 which correspond to an image to be displayed.
Consequently, the positions of all pixels 15 are successively scanned, and wall charge is written into only those pixels 15 which correspond to the image. Thus, n scanning drivers 22 apply sustain pulses B to all of n scanning electrodes 12, and single sustain driver 24 applies sustain pulses A to all of n sustain electrodes 13.
In this instance, since the generation timings of sustain pulses A applied to scanning electrodes 12 and sustain pulses B applied to sustain electrodes 13 are different from each other, a first condition wherein current flows from scanning electrodes 12 to sustain electrodes 13 as seen in FIG. 1 and a second condition (not shown) wherein current flows from sustain electrodes 13 to scanning electrodes 12 occur alternately.
Since the direction of sustain pulses supplied to surface discharge electrodes 11 is reversed between the first condition and the second condition, discharge occurs only at the positions of those pixels 15 to which the wall charge has been written, and only the phosphors of those pixels 15 emit light to display an image.
However, when an image is displayed in such a manner as described above, the sustain pulses to be applied to electrodes 12, 13 are required to have a peak value of approximately several hundreds volt and a frequency of several hundreds kilohertz since electrodes 12, 13 cause the phosphors to emit light by discharge.
In plasma display panel 1 described above, the feeding direction between electrodes 12, 13 is reversed between the first condition and the second condition. In particular, in the first condition, current is fed from the left to the right in all of surface discharge electrodes 11, and this is reversed in the second condition.
If current is fed in the same direction in the large number of surface discharge electrodes 11 in this manner, then since electric fields and magnetic fields are generated in high intensities, they have a bad influence as magnetic noise and electric field noise upon the surroundings.
Further, current supplied from one end of each of electrodes 12 to 14 flows through the other end of the electrode to the grounding wiring line on the rear face, and since a large amount of current flows through the grounding wiring lines, excessively high ground noise is generated.
Furthermore, when sustain pulses pass through surface discharge electrodes 11, since the potential difference between adjacent surface discharge electrodes 11 is large, discharge occurs between surf ace discharge electrodes 11 and wall charge is sometimes written in error into those pixels 15 which are not to be lit.
In this instance, since those pixels 15 which are not to be lit are lit in error, the display quality of an image is deteriorated as a whole.
Similarly, since also the potential differences between surface discharge electrodes 11 and data electrodes 14 are large, wall charge is sometimes written in error into data electrodes 14, and this deteriorates the image quality.